Process for the preparation of aqueous magnetic ink character recognition ink-jet ink compositions

A process for preparing a metal oxide pre-dispersion for MICR ink-jet ink applications comprising the steps of:

• (1) mixing a surfactant with distilled water at high speed to form an aqueous solution;
• (2) continuing to mix said aqueous solution at high speed while slowly adding a metal oxide pigment to said aqueous solution;
• (3) adding said aqueous solution containing said metal oxide pigment to a milling apparatus lacking any grinding media and mixing for an amount of time sufficient to obtain a homogeneous suspension of said metal oxide pigment in said surfactant solution;
• (4) removing said suspension to a conventional grinding apparatus including grinding media and milling for a period of several days or for a time sufficient to reduce the metal oxide particle size;
• (5) removing said suspension to a non-conventional grinding apparatus for further milling;
• and
• (6) filtering said suspension in a series of step down filters to remove any particles having a particle size in excess of the nozzle size of the print head on a printing device.